A process for the production of milk clotting enzyme from Aspergillus oryzae MTCC 5341

An improved process for production of milk clotting enzyme from Aspergillus oryzne- MTCC5341: A fungal source, identified as Aspergillus oryzae, MTCC 5341 has been isolated that produces the highest milk-clotting enzyme reported (30,000 U/ g dry bran) when grown on wheat bran containing 4 % defatted soy flour (DSF) and 2 % skim milk powder. The pH of the medium is critical for optimal production of the enzymes, with milk-clotting activity being produced at pH 6.3. At this pH, the ratio of milk-clotting activity : acid protease activity of 450 : 1 is obtained. Milk clotting enzyme was stable in a pH range of 4.0 - 8.0 with optimal activity at pH 6.3. Enzyme showed low thermal stability and lost 50% of its activity at 50°C when held for 15 min indicating its suitability as a rennet substitute. Milk clotting activity could be recovered by ultrafilteration (85% recovery) or freeze-drying with added 1 % alginate (70% recovery). The enzyme can be stored in either form at 4°C for a period of 2 months with < 30 % loss in activity.